Assistant Professor of Radiology
Stanford University School of Medicine
Department of Radiology
Richard M. Lucas Center for Imaging
1201 Welch Road, Room P269
Stanford, CA 94305-5488
MR angiography: MR provides an high-resolution, radiation-free means of evaluating vessel number, size, course, and patency. For example, in patients with acute or chronic leg swelling, MR may be used to identify the presence and extent of venous thrombosis, as well as any anatomic cause predisposing a patient to forming a venous clot. For those with venous stents, MR may be used to confirm continued patency of the stent. MR may also be used to thoroughly evaluate patients prior to planned surgery. For example, MR imaging of patients being considered for renal donation for transplant reveals the presence of accessory renal arteries, variant venous anatomy, unsuspected renal masses, or hydronephrosis.
Figure 1: High resolution post-contrast axial MR image of the legs demonstrates swelling of the left leg, and an expansile filling defect in the left popliteal vein, indicating an acute thrombus.
Figure 2: Curved planar reformatted image from post-contrast MR images demonstrates anatomy consistent with May-Thurner syndrome, with narrowing of the left common iliac vein between the crossing right common iliac artery and the spine. This compression predisposes patients to thrombosis within the left lower extremity.
Figure 3: Coronal post-contrast MR image demonstrates homogeneous opacification of a stent in the left common iliac vein, indicating stent patency.
Figure 4: Volume rendered images generated from multiphasic MR images of a potential renal donor demonstrate prehilar branching of the renal arteries, and a circumaortic left renal vein.
Interventional MR: Approximately 600,000 hysterectomies are performed every year, with more than 30% of these surgeries done to address the symptoms of uterine fibroids. While surgery and minimally invasive methods such as uterine artery embolization (UAE) have important roles in the management of patients with uterine fibroids, MR guided high intensity focused ultrasound (MRgHIFU) is an entirely non-invasive method that may be used to treat a subset of these patients.
Figure 5: Sagittal T2 weighted MR image shows an enlarged uterus with several hypointense uterine fibroids. Fibroids may cause excessive menstrual bleeding, and/or pain from mass effect on adjacent pelvic organs such as the bladder or rectum.